a mole whom Nikita is using to destroy Division from the inside. Other recruits include Jaden (Tiffany Hines) and Thom (Ashton Holmes) but their characters are later killed off by Nathan (Thad Luckinbill) and Alex respectively. Dillon Casey portrays the role of Sean Pierce, a former Navy SEAL sent to Division directly from Oversight. Noah Bean portrays Ryan Fletcher, an agent in the CIA, but later takes over Division. Some other notable recurring characters include Ari Tasarov (Peter Outerbridge), Sergei Semak (Peter J. Lucas), Roan (Rob Stewart), and Nathan Colville (Thad Luckinbill). Main Maggie Q as Nikita Mears: The show's central protagonist and titular character, Nikita is a spy and assassin who has vowed to destroy the secret agency that trained her: Division. She is the mentor and close confidant of Alex, and she is a former protege of Amanda. She gains close ties with majority of the people she works with, such as Michael - who eventually becomes her love interest - Seymour Birkhoff, Owen Elliot and Ryan Fletcher. Shane West as Michael Bishop: An ex-Division agent who fell in love with Nikita and joined forces with her to destroy his former employers. Lyndsy Fonseca as Alexandra "Alex" Udinov: The young woman Nikita rescued the night Division killed her family. She trained to destroy Division, and she also seeks revenge against Division for the massacre of her family. She is Amanda's former protege and Nikita's very close friend. Aaron Stanford as Seymour Birkhoff/Lionel Peller: A computer genius, hacker, and nonconformist. Former employee of Division until he sided with Nikita in order to bring order to the underworld of black ops and corrupted crimes. Ashton Holmes as Thom: A Division assassin who was recruited before Alex. Tiffany Hines as Jaden: A Division assassin who was recruited before Alex. Melinda Clarke as Helen "Amanda" Collins: The show's main antagonist in the third and fourth season, Amanda is a master manipulator, interrogator, and psychologist. She is also a former head of Division as well as an enemy and former mentor of Nikita and Alex. Xander Berkeley as Percival "Percy" Rose: The show's main antagonist in the first and second season, Percy is the former head of Division who involves his government access with black market crimes and assassination of powerful people around the world. Dillon Casey as Sean Pierce: A former Navy SEAL hired to keep an eye on Division and the